Calculator API — 135+ Online Calculators | YEB

135+ online calculators via REST API. Finance, health, math, construction, physics and more. Evaluate formulas, search calculators, get definitions.

API FAQ

Ottieni chiave API Acquista crediti

Try it live

All 135 calculators are available for free on the web app:

Open calculator.yeb.to

✓

135+ calculators
Finance, health, math, construction, physics, chemistry, biology, statistics, and more.

✓

16 categories
Organized by topic for easy discovery and integration.

✓

30 languages
Translated titles, descriptions, and input/output labels.

Endpoint:

99.9 % Disponibilità

7ms Risposta

20 req/s

0.001 Crediti / richiesta

Calculate


POST https://api.yeb.to/v1/calculator/calculate

Parametro	Tipo	Rich.	Descrizione
`api_key`	string	sì	Your API key
`calculator_id`	integer	sì	ID of the calculator to evaluate
`inputs`	object	sì	Input values as key-value pairs (e.g. {"length": 10, "width": 5})
`units`	object	opz.	Selected units per input/output (e.g. {"length": "m", "area": "m2"})

Esempio

curl -X POST https://api.yeb.to/v1/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "calculator_id": 1,
  "inputs": {
    "value": 200,
    "percentage": 15
  },
  "units": {}
}'

Esempio di risposta

{
  "calculator_id": 1,
  "calculator_slug": "percentage",
  "results": {
    "result": {
      "value": 30,
      "unit": null
    },
    "inverse": {
      "value": 7.5,
      "unit": null
    }
  },
  "credits_spent": 0.001,
  "credits_left": 99.99,
  "response_code": 200,
  "response_time_ms": 12
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Codici di risposta

Codice	Descrizione
200 Success	Richiesta elaborata OK.
400 Bad Request	Validazione input fallita.
401 Unauthorized	Chiave API mancante o errata.
403 Forbidden	Chiave inattiva o non consentita.
429 Rate Limit	Troppe richieste.
500 Server Error	Errore imprevisto.

Calculate

calculator/calculate 0.0010 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Calculator ID

body · string · required

Inputs

body · string · required

Units

body · string

Code Samples

Response

Status: —

Headers

Body

List Calculators


POST https://api.yeb.to/v1/calculator/list

Parametro	Tipo	Rich.	Descrizione
`api_key`	string	sì	Your API key
`category`	string	opz.	Filter by category slug (e.g. "finance", "health", "math")
`locale`	string	opz.	Language code for translated titles (default: en)
`limit`	integer	opz.	Max results, 1–100 (default: 50)
`offset`	integer	opz.	Skip N results for pagination (default: 0)

Esempio

curl -X POST https://api.yeb.to/v1/calculator/list \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "category": "finance",
  "locale": "en",
  "limit": 5
}'

Esempio di risposta

{
  "total": 14,
  "offset": 0,
  "limit": 5,
  "calculators": [
    {
      "id": 1,
      "slug": "percentage",
      "title": "Percentage Calculator",
      "short_description": "Calculate what X% of Y is.",
      "category": "finance"
    },
    {
      "id": 2,
      "slug": "percentage-change",
      "title": "Percentage Change Calculator",
      "short_description": "Calculate percentage change between two values.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "credits_left": 100,
  "response_code": 200,
  "response_time_ms": 8
}

{
  "error": "Invalid limit parameter",
  "response_code": 400,
  "response_time_ms": 2
}

Codici di risposta

Codice	Descrizione
200 Success	Richiesta elaborata OK.
400 Bad Request	Validazione input fallita.
401 Unauthorized	Chiave API mancante o errata.
403 Forbidden	Chiave inattiva o non consentita.
429 Rate Limit	Troppe richieste.
500 Server Error	Errore imprevisto.

List Calculators

calculator/list 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Code Samples

Response

Status: —

Headers

Body

Calculator Info


POST https://api.yeb.to/v1/calculator/info

Parametro	Tipo	Rich.	Descrizione
`api_key`	string	sì	Your API key
`slug`	string	opz.	Calculator slug (e.g. "bmi", "mortgage")
`calculator_id`	integer	opz.	Calculator ID (alternative to slug)
`locale`	string	opz.	Language code (default: en)

Esempio

curl -X POST https://api.yeb.to/v1/calculator/info \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "slug": "bmi"
}'

Esempio di risposta

{
  "id": 25,
  "slug": "bmi",
  "title": "BMI Calculator",
  "short_description": "Calculate your Body Mass Index.",
  "formula": {
    "inputs": [
      {"key": "weight", "type": "number", "default": 70, "unit_group": "mass", "default_unit": "kg"},
      {"key": "height", "type": "number", "default": 175, "unit_group": "height", "default_unit": "cm"}
    ],
    "outputs": [
      {"key": "bmi", "expression": "weight / (height * height)", "precision": 1},
      {"key": "category", "expression": "..."}
    ],
    "unit_groups": {
      "mass": {"kg": 1, "lb": 0.453592},
      "height": {"m": 1, "cm": 0.01, "in": 0.0254}
    }
  },
  "input_labels": {"weight": "Weight", "height": "Height"},
  "output_labels": {"bmi": "Your BMI", "category": "Category"},
  "category": {"slug": "health", "name": "Health & Fitness"},
  "credits_spent": 0,
  "response_code": 200
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Codici di risposta

Codice	Descrizione
200 Success	Richiesta elaborata OK.
400 Bad Request	Validazione input fallita.
401 Unauthorized	Chiave API mancante o errata.
403 Forbidden	Chiave inattiva o non consentita.
429 Rate Limit	Troppe richieste.
500 Server Error	Errore imprevisto.

Calculator Info

calculator/info 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Slug

body · string

Calculator ID

body · string

Locale

body · string

Code Samples

Response

Status: —

Headers

Body

Search Calculators


POST https://api.yeb.to/v1/calculator/search

Parametro	Tipo	Rich.	Descrizione
`api_key`	string	sì	Your API key
`query`	string	sì	Search query (minimum 2 characters)
`locale`	string	opz.	Language code (default: en)
`limit`	integer	opz.	Max results, 1–50 (default: 20)

Esempio

curl -X POST https://api.yeb.to/v1/calculator/search \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "query": "mortgage",
  "locale": "en",
  "limit": 5
}'

Esempio di risposta

{
  "query": "mortgage",
  "results": [
    {
      "id": 5,
      "slug": "mortgage",
      "title": "Mortgage Calculator",
      "short_description": "Calculate monthly mortgage payment, total interest, and total amount paid.",
      "category": "finance"
    },
    {
      "id": 9,
      "slug": "amortization",
      "title": "Amortization Calculator",
      "short_description": "See how each payment splits between principal and interest.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "response_code": 200,
  "response_time_ms": 15
}

{
  "error": "Query must be at least 2 characters",
  "response_code": 400,
  "response_time_ms": 2
}

Codici di risposta

Codice	Descrizione
200 Success	Richiesta elaborata OK.
400 Bad Request	Validazione input fallita.
401 Unauthorized	Chiave API mancante o errata.
403 Forbidden	Chiave inattiva o non consentita.
429 Rate Limit	Troppe richieste.
500 Server Error	Errore imprevisto.

Search Calculators

calculator/search 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Query

body · string · required

Locale

body · string

Limit

body · string

Code Samples

Response

Status: —

Headers

Body

Calculator API — 135+ Online Calculators | YEB — Practical Guide

A hands-on guide to the Calculator API: 135+ online calculators across 16 categories, formula evaluation with unit conversion, multilingual support in 30 languages, and how to integrate it all into your application.

Last updated: 20 mar 2026, 22:48 API Version: v1 Burst: 20 req/s Latency: 7 ms

#What the Calculator API does

The Calculator API provides 4 endpoints for accessing 135+ online calculators: evaluate formulas with unit conversion, list and search calculators, and get complete formula definitions — all via simple POST requests.

Key advantage: three out of four endpoints are completely free. Only the Calculate endpoint costs credits (0.001 per request). Formula definitions are open, so you can also evaluate client-side if preferred.

#Endpoints at a glance

Endpoint	What it does	Credits
`POST /v1/calculator/calculate`	Evaluate a calculator formula with inputs and unit conversion	0.001
`POST /v1/calculator/list`	List all calculators, optionally filtered by category	FREE
`POST /v1/calculator/info`	Get full formula definition, inputs, outputs, and unit groups	FREE
`POST /v1/calculator/search`	Search calculators by keyword across all categories	FREE

#Available categories

135 calculators are organized into 16 categories:

Category	Slug	Count	Examples
Finance	`finance`	14	Percentage, Mortgage, Compound Interest, ROI, CAGR
Salary & Tax	`salary-tax`	10	Gross/Net, VAT, Tip, Discount, Margin, Retirement
Health & Fitness	`health`	12	BMI, Calories (TDEE), BMR, Body Fat, Protein
Pregnancy	`pregnancy`	5	Due Date, Ovulation, Period, Fertility Window
Math	`math`	10	Fraction, Quadratic Formula, GPA, Logarithm
Conversion	`conversion`	10	Weight, Length, Temperature, Speed, Pressure
Time & Date	`time-date`	7	Age, Days Between Dates, Countdown, Time Zone
Construction	`construction`	9	Concrete, Brick, Tile, Paint, Roofing
Automotive	`automotive`	8	Fuel Cost, Tire Size, Horsepower, 0-100 km/h
Physics	`physics`	8	Free Fall, Force, Kinetic Energy, Projectile Motion
Chemistry	`chemistry`	7	Molar Mass, pH, Dilution, Percent Yield
Biology	`biology`	6	Punnett Square, DNA, Bacteria Growth
Statistics	`statistics`	8	Std Deviation, Confidence Interval, Z-Score
Food & Cooking	`food`	8	Pizza, Coffee, Grams to Cups, Recipe Scaler
Sports	`sports`	7	Calories Burned, Pace, Marathon, VO2 Max
Fun & Viral	`fun`	6	Love Compatibility, Lucky Number, Zodiac

#How the formula system works

Each calculator stores its formula as a JSON definition with inputs, outputs, unit groups, and constants. The formula engine supports arithmetic, ternary expressions, and built-in math functions (sqrt, sin, cos, log, pow, min, max, etc.).

Use the info endpoint to retrieve the complete formula definition for any calculator. You can then evaluate it server-side via the calculate endpoint, or implement client-side evaluation using the same expression language.

Unit conversion is automatic. Define unit groups (e.g. length: m, cm, ft, in) with conversion factors. Inputs are normalized to base units before evaluation, and outputs are converted to the user's selected display unit.

#Multilingual support

All 135 calculators are translated into 30 languages: English, Bulgarian, Spanish, German, French, Italian, Portuguese, Russian, Polish, Dutch, Turkish, Czech, Romanian, Hungarian, Ukrainian, Swedish, Danish, Finnish, Norwegian, Greek, Arabic, Hebrew, Japanese, Korean, Chinese (Simplified & Traditional), Thai, Vietnamese, Indonesian, and Malay.

Use the locale parameter on the list, info, and search endpoints to get translated titles, descriptions, input/output labels, and educational content.

#Common use cases

Embedded calculators — add interactive calculators to your website or app
Education platforms — provide step-by-step calculations for students
Health & fitness apps — BMI, calorie, and body composition calculations
Real estate tools — mortgage, loan, and amortization calculations
Construction estimators — material quantity and cost calculators
Chatbots & AI assistants — answer calculation questions programmatically
Comparison tools — evaluate multiple scenarios with different inputs

#Try it live

All 135 calculators are available for free on calculator.yeb.to. Each calculator has an interactive widget, educational article, FAQ section, and SEO-optimized pages in 30 languages. The web app uses the same formula engine as the API.

Domande frequenti

135+ calculators across 16 categories: finance (percentage, mortgage, compound interest, ROI), health (BMI, calories, body fat), math (quadratic formula, logarithm), construction (concrete, brick, tile), physics (free fall, kinetic energy), chemistry (molar mass, pH), and more.

The Calculate endpoint costs 0.001 credits per request. List, Info, and Search endpoints are completely free. Sign up to get free credits.

All 135 calculators are translated into 30 languages including English, Spanish, German, French, Bulgarian, Russian, Japanese, Chinese, Arabic, and more. Use the locale parameter to get translated content.

Yes! Use the Info endpoint with a calculator slug to get the complete formula definition including inputs, outputs, expressions, unit groups, and constants. You can evaluate formulas client-side or via the Calculate endpoint.

Each calculator defines unit groups with conversion factors. When you send a units parameter with your Calculate request, inputs are automatically converted to base units before evaluation, and outputs are converted to your selected display units.

Sì. Ogni richiesta, anche quelle che generano errori, consuma crediti. I tuoi crediti sono legati al numero di richieste, indipendentemente dal successo o dal fallimento. Se l'errore è chiaramente dovuto a un problema della piattaforma da parte nostra, ripristineremo i crediti interessati (nessun rimborso in contanti).

Contattaci a [email protected]. Prendiamo i feedback seriamente—se la tua segnalazione di bug o richiesta di funzionalità è significativa, possiamo correggere o migliorare l'API rapidamente e concederti 50 crediti gratuiti come ringraziamento.

Dipende dall'API e a volte anche dall'endpoint. Alcuni endpoint utilizzano dati da fonti esterne, che possono avere limiti più rigorosi. Imponiamo anche limiti per prevenire abusi e mantenere la nostra piattaforma stabile. Consulta la documentazione per il limite specifico di ogni endpoint.

Operiamo con un sistema di crediti. I crediti sono unità prepagate e non rimborsabili che spendi per chiamate API e strumenti. I crediti vengono consumati in ordine FIFO (i più vecchi per primi) e sono validi per 12 mesi dalla data di acquisto. La dashboard mostra ogni data di acquisto e la sua scadenza.

Sì. Tutti i crediti acquistati (inclusi i saldi frazionari) sono validi per 12 mesi dall'acquisto. I crediti non utilizzati scadono automaticamente e vengono eliminati permanentemente alla fine del periodo di validità. I crediti scaduti non possono essere ripristinati o convertiti in contanti o altro valore. Regola transitoria: i crediti acquistati prima del 22 set. 2025 sono trattati come acquistati il 22 set. 2025 e scadono il 22 set. 2026 (salvo diversa scadenza indicata all'acquisto).

Sì—entro il periodo di validità. I crediti non utilizzati rimangono disponibili e vengono riportati di mese in mese fino alla scadenza 12 mesi dopo l'acquisto.

I crediti sono non rimborsabili. Acquista solo ciò di cui hai bisogno—puoi sempre ricaricare in seguito. Se un errore della piattaforma causa un addebito fallito, possiamo ripristinare i crediti interessati dopo indagine. Nessun rimborso in contanti.

I prezzi sono fissati in crediti, non in dollari. Ogni endpoint ha il proprio costo—vedi il badge "Crediti / richiesta" sopra. Saprai sempre esattamente quanto stai spendendo.

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API / Endpoint

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Calculator API — 135+ Online Calculators | YEB

Try it live

Calculate

Esempio

Esempio di risposta

Codici di risposta

Calculate

Parameters

Code Samples

Response

List Calculators

Esempio

Esempio di risposta

Codici di risposta

List Calculators

Parameters

Code Samples

Response

Calculator Info

Esempio

Esempio di risposta

Codici di risposta

Calculator Info

Parameters

Code Samples

Response

Search Calculators

Esempio

Esempio di risposta

Codici di risposta

Search Calculators

Parameters

Code Samples

Response

Calculator API — 135+ Online Calculators | YEB — Practical Guide

#What the Calculator API does

#Endpoints at a glance

#Available categories

#How the formula system works

#Multilingual support

#Common use cases

#Try it live

Domande frequenti

What calculators are available?

How much does it cost?

What languages are supported?

Can I get the formula definition?

How does unit conversion work?

Le richieste con errori contano e costano crediti?

Ho trovato un bug o voglio personalizzazioni nelle API. Cosa faccio?

Qual è il limite di richieste?

Come funzionano il pagamento e l'utilizzo?

I crediti scadono?

I crediti non utilizzati vengono riportati?

Offrite rimborsi?

Quanto costa ogni chiamata API?